The application of heat as an anti-cancer primary or adjuvant treatment continues to prove itself as a clinically viable and successful modality. The number of positive clinical trial outcomes has steadily accumulated since the early 1990s. There is also a growing list of improved technology for thermal ablative procedures. With increasing uses of various heating devices and strategies comes an increasing gap in our knowledge pertaining to the biology and physiology of thermal therapy-associated temperature gradients. A further gap in knowledge exists in our limited abilities to intelligently use radiation therapy or other adjuvants such as anti- vascular compounds to maximize the anti-tumor effects of various thermal therapies. We have identified this missing knowledge as a largely unmet opportunity to advance the field of thermal therapy and significantly enhance cancer treatment options. It is our conviction that detailed biological and physiological investigations related to the application of heat against various malignancies will empower clinical multi-modality therapy by supplying scientifically validated rationale. Because of the complex and multi-disciplinary nature of this work, the principal investigator has assembled a new team of experts in tumor radiation biology, physiology, engineering and physics at the University of Arkansas for Medical Sciences. Murine and human cancer cell lines will be grown in mice. Using these tumor models we aim to identify reoxygenation patterns induced by conventional hyperthermia and the mechanisms as well as potential benefits of inducing vascular thermotolerance in tumor tissue. The injury patterns and reoxygenation of tumor tissue after severe heating with and without the addition of the novel anti-vascular agents arsenic trioxide (ATO) and gold-nanoparticle-bound tumor necrosis factor-1 (Pt-cAu-TNF) will also be characterized. Subsequently, we will design precise sequences of combined heat, anti-vascular agents and radiation therapy to obtain optimal anti-tumor effects. The central hypothesis of this work is two-fold: (1) exposure of tumor tissue to mild hyperthermia improves tumor oxygenation and (2) severe heating is cytotoxic to varying portions of the tumor, especially with anti-vascular treatment, yet it increases oxygenation in sub-lethally treated areas thereby enhancing radiation therapy. We will use well established methods in cell biology and physiological measurement techniques as well as cutting-edge non-invasive imaging and heat application with advanced optical and radiographic imagers and ultrasound. Intravital microscopy will be used to study tumors grown in window chambers to longitudinally investigate mechanisms of treatment effects in vivo. Tumors grown and treated in other locations will be studied with detailed immunochemical analysis to elucidate effects on the tumor vasculature stability and composition. The data obtained will be both scientifically valuable and clinically practical, helping to refine the possibilities for effective translational research in the field of thermal and radiation therapy. The main focus of this work is to define the rationale for combining thermal therapy with radiation therapy and explain in detail the response of tumor and normal tissue to traditional hyperthermia temperatures or thermal ablation. A recurring theme of the work is that while the cumulative equivalent minutes at 430C (CEM430C) are usually quite low in traditional hyperthermia applications, the CEM 430C can be several orders of magnitude greater at the tip of a 600C thermal ablation probe yet we observe common biological changes in the tumor in both cases, depending on the exact location in the tissue that is being studied. Tumor blood flow and oxygenation is significantly increased in certain areas of the tumor. Our primary focus is to define where this happens, why this happens and how it may influence patient response to other applied therapies.